The present invention relates generally to an apparatus for mixing fluent material in which vessels are agitated eccentrically to produce a vortex mixing action. In particular, the mixer of the present invention is intended for use in laboratories and the like to agitate vessels, such as test tubes.
Laboratory mixers are known in the art. A typical apparatus is illustrated in U.S. Pat. No. 3,850,580. In such mixers, the vessel, such as a test tube, beaker or flask, is manually held against a resilient top surface, which is driven eccentrically. In this manner, the vessel is agitated. The surface is large enough to accommodate several test tubes or a flask. The degree of agitation transmitted to a vessel depends upon the force with which the vessel is held against the resilient surface.
Such a mixer, however, is not suitable for situations requiring a mass uniform mixing of test tubes. It is not possible to uniformly mix test tubes where multiple test tubes are manually pressed against a resilient surface simultaneously, especially where the degree of agitation is dependent upon the force applied. The human hand simply can not provide a uniform force in such cases.
Another mixer is known from U.S. Pat. No. 3,061,280. Here, a vessel, usually a test tube, is held in or against a cupshaped member which is eccentrically driven to agitate the vessel. The amount or degree of agitation can be manually adjusted by changing the throw or rotational speed of the eccentric drive.
With this type of mixer, it is not possible to agitate several test tubes at one time and manual adjustment or the agitation can be difficult when the vessel is being manually held against the eccentrically driven member.